The present invention relates to the new and distinct hardy, herbaceous, Hibiscus plant, Hibiscus ‘Summer Carnival’ discovered by the inventor on Aug. 10, 2014 in the research fields of a wholesale perennial nursery in Zeeland, Mich. The new plant is a branch chimeral sport selected from an unnamed unreleased proprietary seedling. During the trial process the new plant was assigned the breeder code labeled 14-SP-HIB-317. Both parents have a complex mixture of species in them, comprising the species: moscheutos and coccineus. Hibiscus ‘Summer Carnival’ was first asexually propagated by shoot tip cuttings on Aug. 10, 2014 and later by sterile shoot-tip tissue culture at the same nursery in Zeeland, Mich. The resultant asexually propagated plants have been found to be stable and true to type in successive generations of asexual reproduction.